CN117179734A

CN117179734A - Image uniformity correction method, device, computer equipment and storage medium

Info

Publication number: CN117179734A
Application number: CN202210610780.6A
Authority: CN
Inventors: 朱浩; 周晓东
Original assignee: Shanghai United Imaging Healthcare Co Ltd
Current assignee: Shanghai United Imaging Healthcare Co Ltd
Priority date: 2022-05-31
Filing date: 2022-05-31
Publication date: 2023-12-08

Abstract

The application relates to an image uniformity correction method, an image uniformity correction device, computer equipment and a storage medium. The method comprises the following steps: respectively acquiring a heart image sequence acquired by a local coil and a reference image acquired by a body coil; performing uniformity correction processing on the heart image sequence according to the reference image to obtain a corrected heart image sequence; and generating a target magnetic resonance image of the heart part according to the corrected heart image sequence. The acquisition time of the heart image sequence is different from the acquisition time of the reference image, and the heart image sequence and the reference image correspond to a set breath-hold period of a heart part of a scanning object. Thus, the heart image sequence acquired in the set breath-hold period is aligned with the reference image, and the influence of respiratory motion is reduced. In addition, the heart image acquired by the body coil is used as a reference image, and the uniformity of the heart image sequence acquired by the local coil is corrected, so that the uniformity of the magnetic resonance image is improved.

Description

Image uniformity correction method, device, computer equipment and storage medium

Technical Field

The present application relates to the field of magnetic resonance imaging technology, and in particular, to an image uniformity correction method, an image uniformity correction device, a computer device, and a storage medium.

Background

Magnetic resonance imaging (Magnetic Resonance Imaging, MRI) equipment is mainly composed of a main magnet system, a gradient system, a radio frequency system, a computer system and other auxiliary equipment. The main functions of the radio frequency system are to apply radio frequency excitation and receive nuclear magnetic resonance signals. The radio frequency system can generate a digital pulse waveform according to the selected pulse sequence, the digital pulse waveform is converted into an analog signal through a digital-to-analog converter, the analog signal is modulated and amplified to drive a transmitting coil of the radio frequency system, atomic nuclei in an imaging area are excited to generate resonance, and therefore a magnetic resonance signal is generated; the magnetic resonance signal can be received by a receiving coil of a radio frequency system, amplified by a preamplifier, demodulated, filtered, digital-to-analog converted, preprocessed, fourier transformed and the like, and finally a nuclear magnetic resonance image is reconstructed. The receiving coil can directly influence the signal-to-noise ratio of the image, and theoretically, the closer the receiving coil is to the inspected part, the stronger the received signal is; the smaller the volume of the coil, the lower the noise it receives. The receiving coils of the radio frequency system can be divided into orthogonal head coils, orthogonal body coils, orthogonal knee joint coils, orthogonal ankle joint coils, head-neck joint phased array coils, body phased array coils, full-spine phased array coils, surface coils, and special coils such as mammary gland, intrarectal, intrauterine cavities and the like according to different structures and examination purposes. Wherein the phased array coil/local coil is composed of a plurality of surface coils together, which can provide a finer MRI examination of the relevant region. However, since the local coil is a multi-channel array coil, the spatial sensitivity distribution of each coil unit is uneven, the signal near the coil area is strong, but the signal also drops sharply with increasing distance from the coil area, so that the resultant image of the multi-channel array coil is uneven, and the local coil cannot see the image of the whole scan Field of View (FOV).

In the related art, when performing cardiac magnetic resonance imaging, a combined image of each coil unit image in a local coil is used as a reference image, and a cardiac sequence image acquired by the local coil is subjected to uniformity correction, so that a uniform magnetic resonance image is obtained.

However, in the related art, each time a scan is performed, uniformity correction needs to be performed on a heart image, which has a large calculation amount and a slow imaging speed.

Disclosure of Invention

In view of the foregoing, it is desirable to provide an image uniformity correction method, apparatus, computer device, and storage medium that can improve the uniformity of a magnetic resonance image.

In a first aspect, the present application provides an image uniformity correction method, the method comprising:

respectively acquiring a heart image sequence acquired by a local coil and a reference image acquired by a body coil; the acquisition time of the heart image sequence is different from the acquisition time of the reference image, and the heart image sequence and the reference image correspond to a set breath-hold period of a heart part of a scanning object;

performing uniformity correction processing on the heart image sequence according to the reference image to obtain a corrected heart image sequence;

and generating a target magnetic resonance image of the heart part according to the corrected heart image sequence.

In one embodiment, acquiring a sequence of cardiac images acquired by a local coil includes:

collecting a plurality of K space data sets of the heart part in a set breath-hold period through a local coil;

and performing first image transformation processing on each K space data set to obtain a heart image sequence.

In one embodiment, acquiring a reference image acquired by a body coil includes:

undersampling the heart part through the body coil in a set breath-hold period to obtain a partial K space data set;

and performing second image transformation processing on the partial K space data set to obtain a reference image.

In one embodiment, performing a first image transformation on each K-space dataset to obtain a sequence of cardiac images, including:

acquiring candidate K space data sets with the same filling positions as part of the K space data sets from each K space data set;

coil channel combination is carried out on each candidate K space data set, and a first combined K space data set corresponding to each candidate K space data set is obtained;

and carrying out Fourier transform on each first combined K space data set to obtain a heart image sequence.

In one embodiment, performing a second image transformation on the partial K-space dataset to obtain a reference image, including:

Performing coil channel combination on the partial K space data set to obtain a second combined K space data set corresponding to the partial K space data set;

performing Fourier transform on the second combined K space data set to obtain an initial image of the heart part;

and carrying out interpolation processing on the initial image to obtain a reference image.

In one embodiment, performing a uniformity correction process on a sequence of cardiac images from a reference image includes:

determining a coil sensitivity distribution factor corresponding to each heart image in the heart image sequence according to the reference image and the heart image sequence;

and carrying out uniformity correction processing on each heart image according to the coil sensitivity distribution factors corresponding to each heart image to obtain a corrected heart image sequence.

In one embodiment, generating a target magnetic resonance image of a heart site from the corrected sequence of heart images comprises:

and based on the corrected heart image sequence, carrying out fusion processing on the plurality of heart images subjected to uniformity correction processing to obtain a target magnetic resonance image of the heart part.

In a second aspect, the present application also provides an image uniformity correction apparatus, including:

the acquisition module is used for respectively acquiring a heart image sequence acquired by the local coil and a reference image acquired by the body coil; the acquisition time of the heart image sequence is different from the acquisition time of the reference image, and the heart image sequence and the reference image correspond to a set breath-hold period of a heart part of a scanning object;

The correction module is used for carrying out uniformity correction processing on the heart image sequence according to the reference image to obtain a corrected heart image sequence;

and the imaging module is used for generating a target magnetic resonance image of the heart part according to the corrected heart image sequence.

In a third aspect, the present application also provides a computer device comprising a memory storing a computer program and a processor implementing the steps of any of the method embodiments of the first aspect described above when the computer program is executed by the processor.

In a fourth aspect, the present application also provides a computer readable storage medium having stored thereon a computer program which when executed by a processor performs the steps of any of the method embodiments of the first aspect described above.

In a fifth aspect, the application also provides a computer program product comprising a computer program which, when executed by a processor, implements the steps of any of the method embodiments of the first aspect described above.

The image uniformity correction method, the image uniformity correction device, the computer equipment and the storage medium respectively acquire a heart image sequence acquired by the local coil and a reference image acquired by the body coil. Further, uniformity correction processing is performed on the heart image sequence according to the reference image, so that a corrected heart image sequence is obtained. Then, a target magnetic resonance image of the heart site is generated from the corrected cardiac image sequence. The acquisition time of the heart image sequence is different from the acquisition time of the reference image, and the heart image sequence and the reference image correspond to a set breath-hold period of a heart part of a scanning object. That is, the method acquires images of the heart part of the scanned object through the body coil and the local coil in a set breath-hold period, so that the alignment of a heart image sequence and a reference image can be ensured, and the influence of respiratory motion is reduced. In addition, the heart image acquired by the body coil is used as a reference image, and the uniformity of the heart image sequence acquired by the local coil is corrected, so that the uniformity of the magnetic resonance image is improved.

Drawings

FIG. 1 is a flow chart of an image uniformity correction method according to an embodiment;

FIG. 2 is a schematic diagram of a process for acquiring a sequence of heart images according to one embodiment;

FIG. 3 is a schematic diagram of a reference image acquisition process in one embodiment;

FIG. 4 is a schematic diagram of a scan sequence in one embodiment;

FIG. 5 is a flow chart of a uniformity correction process in one embodiment;

FIG. 6 is a flowchart of an image uniformity correction method according to another embodiment;

FIG. 7 is a flowchart of a method for image uniformity correction according to yet another embodiment;

FIG. 8 is a block diagram showing an image uniformity correction apparatus in accordance with one embodiment;

fig. 9 is an internal structural diagram of a computer device in one embodiment.

Detailed Description

The present application will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present application more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.

The physical basis of the MRI technology is nuclear magnetic resonance (Nuclear Magnetic Resonance, NMR) phenomenon, the microstructure of a substance can be studied by utilizing the NMR phenomenon, different radio frequency pulse sequences are used for exciting biological tissues to enable the biological tissues to resonate so as to generate magnetic resonance signals, then linear gradient fields are used for carrying out space coding on the magnetic resonance signals, and the characteristics of relaxation time, proton density and the like of the tissues to be detected are utilized for carrying out image reconstruction on information received by a receiving coil, so that a final magnetic resonance image is obtained.

However, due to homogeneity problems of the main magnetic field, the radio frequency transmit field or the radio frequency receive field, the reconstructed image often has non-uniformities in magnetic resonance imaging. Therefore, in order to obtain a uniform magnetic resonance image, correction of image uniformity is required.

In correcting the uniformity of a heart image, the following two methods are generally adopted in the related art:

(1) And taking the combined image of each coil unit image in the local coil as a reference image, and carrying out uniformity correction on the heart image sequence acquired by the local coil. The method needs to correct one image every time of scanning, and has large calculated amount and low imaging speed.

(2) The reference image obtained by pre-scanning is acquired through a local coil or a body coil, and then the heart image sequence is acquired through the local coil. Further, a plurality of heart images in the heart image sequence are fused to obtain a magnetic resonance image of the heart part, and then the uniformity correction is carried out on the magnetic resonance image of the heart part by adopting a reference image to obtain a target magnetic resonance image. According to the method, the reference image is acquired before the heart image sequence is acquired, the position of the local coil which is actually imaged relative to the scanned object can be changed from the position of the local coil when the reference image is acquired, and the image uniformity correction effect is poor under the condition that the sampling position is deviated.

Based on the above, the application provides an image uniformity correction method, which respectively acquires a heart image sequence acquired by a local coil and a reference image acquired by a body coil in a set breath-hold period, and then corrects the heart image sequence by the reference image so as to reconstruct a uniform target magnetic resonance image.

The image uniformity correction method provided by the application can be applied to an image uniformity correction device, the image uniformity correction device can be realized in a software and/or hardware mode, and the device can be integrated in computer equipment with a medical image processing function, for example: an imaging device in a magnetic resonance system, or a terminal, server, etc. outside the magnetic resonance system.

The imaging device in the magnetic resonance system is used for filling magnetic resonance signals into the K space and carrying out image reconstruction according to the K space data to obtain a target magnetic resonance image. Terminals may include, but are not limited to, software running in a physical device, such as an application or client installed on the device, and may also include, but are not limited to, personal computers, notebook computers, smartphones, tablet computers, and portable wearable devices that have applications installed. Servers may include, but are not limited to, at least one standalone server, distributed servers, cloud servers, and server clusters.

The following will specifically describe, by way of examples and with reference to the accompanying drawings, a technical solution of an embodiment of the present application and how the technical solution of the embodiment of the present application solves the above technical problems. The following embodiments may be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments. It should be noted that, in the image uniformity correction method provided by the embodiment of the present application, the execution body may be the above-mentioned computer device, or may be a specific medical imaging device, or may be an image uniformity correction apparatus provided by the present application. It will be apparent that the described embodiments are some, but not all, of the embodiments of the application.

In one embodiment, as shown in fig. 1, there is provided an image uniformity correction method, which is exemplified as the method applied to a computer device, and includes the following steps:

step 110: respectively acquiring a heart image sequence acquired by a local coil and a reference image acquired by a body coil; the acquisition time of the heart image sequence is different from the acquisition time of the reference image, and the heart image sequence and the reference image correspond to a set breath-hold period of a heart part of a scanning object.

Wherein the scan object may be a human or other animal body. The cardiac image sequence and the reference image may be acquired during a pre-scan that calibrates the imaging scan, or during an imaging scan that generates the image, as this embodiment is not limiting.

It should be appreciated that the local coil is a multi-channel array coil comprising a plurality of coil units. When acquiring magnetic resonance signals, each coil unit corresponds to a receiving channel, and different coil units have different spatial/physical positions relative to a region of interest of a scanned object, so that each coil unit has different sensitivity to the magnetic resonance signals excited by the region of interest, i.e. the intensity of the magnetic resonance signals excited by the region of interest received by each coil unit is different. Different array coils are arranged at different parts of the human body. For example, the head is scanned, and array coils corresponding to the head are utilized; and scanning the chest and abdomen, and utilizing an array coil corresponding to the chest and abdomen.

The body coil may be used as either a transmit coil or a receive coil. In particular, by providing a tuning circuit the body coil can be switched between functioning as a transmitting coil and functioning as a receiving coil, in which case the body coil can have two, four, eight etc. receiving channels, each being capable of separately acquiring magnetic resonance signals. In this embodiment, the body coil may be applied in a high magnetic field system with a magnetic field strength of 5T, and has eight receiving channels.

Because the body coil receives a uniform magnetic field, the emitted magnetic field is also uniform in a low field, and the uniformity of the finally obtained image is better, the heart image acquired by the body coil is used as a reference image in the embodiment, so that the uniformity correction is performed on the heart image sequence acquired by the local coil.

In the magnetic resonance imaging, the two conditions of respiratory motion and cardiac motion are considered simultaneously in the cardiac magnetic resonance imaging, so that respiratory motion of a scanned object is restrained through breath-hold scanning, and then an electrocardiographic triggering synchronization device is added to synchronously acquire cardiac motion data.

In one possible implementation, the implementation procedure of step 110 may be: the heart region of the scan subject is scanned by the magnetic resonance system while the scan subject is in a breath-hold state. During the scanning process, a heart image sequence is acquired through a local coil covered on the heart part of the scanning object, a heart image of the heart part of the scanning object is acquired through a body coil, and the heart image acquired through the body coil is used as a reference image.

The heart image sequence and the reference image have different acquisition moments, and the heart image sequence and the reference image correspond to a set breath-hold period of a heart part of a scanning object, so that the sampling positions of the heart image sequence and the reference image can be aligned, and the interference of motion information is reduced. Further, the set breath-hold period may be the same breath-hold period.

In this step, the acquired cardiac image sequence and the reference image may be 2D images or 3D images, which is not limited in this embodiment.

As an example, the heart is a three-dimensional organ with systolic and diastolic motion and a complex structure, and thus the sequence of heart images acquired by the local coil may comprise heart images corresponding to a plurality of moments in diastole and systole.

Step 120: and carrying out uniformity correction processing on the heart image sequence according to the reference image to obtain a corrected heart image sequence.

And performing uniformity correction processing on each heart image in the heart image sequence by referring to the images to obtain a corrected heart image sequence.

As an example, the uniformity correction process may be implemented by using a uniformity correction algorithm, or may be implemented by using a trained neural network model, which is not limited in this embodiment.

In one possible implementation, the uniformity correction process may be implemented by a method of sensitivity encoding reconstruction. Firstly, calculating coil sensitivity distribution factors by using a heart image sequence and a reference image, and then reconstructing K space data acquired by a local coil by using the coil sensitivity distribution factors to obtain a corrected heart image sequence.

Step 130: and generating a target magnetic resonance image of the heart part according to the corrected heart image sequence.

Wherein the target magnetic resonance image of the heart site can be generated directly from the corrected cardiac image sequence. The corrected cardiac image sequence may also be screened first, and a cardiac image with better image quality may be selected to generate a target magnetic resonance image of the cardiac region, which is not limited in this embodiment.

In one possible implementation, the implementation procedure of step 130 may be: and based on the corrected heart image sequence, carrying out fusion processing on the plurality of heart images subjected to uniformity correction processing to obtain a target magnetic resonance image of the heart part.

The fusion processing integrates the characteristic information of a plurality of heart images, so that the target magnetic resonance image can comprise multi-dimensional characteristic information of heart parts, and the heart motion condition of a scanning object can be clearly and accurately reflected.

In addition, the image uniformity method provided in the embodiment can be also applied to image correction of other scanning parts of the scanning object. If the scanning part is in a motion state and the breathing of the patient can influence the motion condition of the scanning part, acquiring an image sequence and a reference image of the scanning part in a breath-hold mode; if the scanning part does not have motion, the image sequence of the scanning part can be acquired through the local coil, then the reference image of the scanning part is acquired through the body coil, and the process does not limit the breathing state of the scanning object.

As an example, when the scan object is a human body, the scan site may be any tissue, such as: lung, prostate, breast, colon, rectum, bladder, ovary, liver, spine, pancreas, cervix, lymph, thyroid, spleen, adrenal gland, thymus, uterus, trachea, etc.

In the above image uniformity correction method, the computer device having a medical image processing function acquires a heart image sequence acquired by the local coil and a reference image acquired by the body coil, respectively, when scanning the heart part of the subject. And then, performing uniformity correction processing on the heart image sequence according to the reference image to obtain a corrected heart image sequence. Finally, a target magnetic resonance image of the heart site is generated from the corrected cardiac image sequence. The acquisition time of the heart image sequence is different from the acquisition time of the reference image, and the heart image sequence and the reference image correspond to a set breath-hold period of a heart part of a scanning object. Therefore, the method sets that images of the heart part of the scanned object are acquired through the body coil and the local coil in the breath-hold period, so that the alignment of a heart image sequence and a reference image can be ensured, and the influence of respiratory motion is reduced. In addition, the heart image acquired by the body coil is used as a reference image, and the uniformity of the heart image sequence acquired by the local coil is corrected, so that the uniformity of the magnetic resonance image is improved.

Based on the above method embodiments, the implementation of acquiring the cardiac image sequence and the reference image will be further described with reference to fig. 2-4.

In one embodiment, as shown in fig. 2, the implementation of acquiring a sequence of cardiac images acquired by a local coil may include the steps of:

step 210: a plurality of K-space data sets of the heart site within a set breath-hold period are acquired by the local coil.

The local coil is used as an array coil and comprises a plurality of coil units, each coil unit can be used as a receiving channel, and correspondingly, the local coil also comprises a plurality of receiving channels.

In this step, K-space data are acquired by a plurality of coil units in the local coil, respectively, resulting in a plurality of K-space data sets. It should be appreciated that each K-space dataset may be fourier transformed to correspondingly generate one cardiac image, and that multiple K-space datasets are used to generate corresponding cardiac image sequences.

After the cardiac region of the scan subject is located, the operator sets corresponding cardiac imaging protocol parameters. When the signal acquisition process is carried out on the heart part through the local coil and the body coil, the heart imaging protocol parameters are not adjusted any more, so that the heart image sequence and the reference image are acquired under the same heart imaging protocol parameters, and the tissue structure positions in the heart image sequence and the tissue structure positions in the reference image are aligned, so that the artifacts caused by position change are reduced.

Wherein the cardiac imaging protocol parameters include at least a scan field of view and an imaging resolution.

Step 220: and performing first image transformation processing on each K space data set to obtain a heart image sequence.

Wherein the first image transformation process may include coil channel merging and fourier transformation.

In one possible implementation, the implementation procedure of step 220 may be: carrying out coil channel combination on the K space data in each K space data set to obtain a first combined K space data set corresponding to each K space data set; and carrying out Fourier transform on the K space data in each first combined K space data set to obtain a heart image sequence.

In this embodiment, based on cardiac imaging protocol parameters, a plurality of K-space data sets of a cardiac region of a scan subject are acquired by a local coil in a breath-hold state of the scan subject, and a cardiac image sequence is generated from the plurality of K-space data sets. Thus, the influence of respiration on the heart image sequence is restrained through breath-hold, and the heart image sequence is acquired in a set breath-hold period, so that respiratory motion artifacts can be reduced, and the image quality is better.

Based on the above method embodiment, after the cardiac image sequence is acquired through the local coil, an image of the cardiac region of the scan object is also acquired through the body coil and used as a reference image, so as to perform uniformity correction on the cardiac image sequence.

In one embodiment, as shown in fig. 3, the implementation process of acquiring the reference image acquired by the body coil may include the following steps:

step 310: the heart site is undersampled by the body coil during a set breath-hold period to obtain a partial K-space dataset.

Since the reference image is acquired through the body coil after the cardiac image sequence is acquired, in order to increase the image acquisition rate and shorten the breath-hold time of the scan object, the reference image may be acquired through the body coil in a downsampling manner. Namely, only partial K space data of the heart part is acquired in the same breath-hold period, so that the data acquisition amount is reduced, and the long breath-hold time of a scanned object is avoided.

In addition, a partial K-space dataset is used to fill a local region of K-space. Since the partial K-space dataset of the K-space central region determines the contrast of the image and the dataset of the K-space peripheral region determines the details of the image, the partial K-space dataset acquired by the body coil may be specifically the data of the K-space central region for the sake of clearly describing the tissue structure information of the heart region.

Step 320: and performing second image transformation processing on the partial K space data set to obtain a reference image.

Wherein the second image transformation process includes a coil channel combining, fourier transform, and interpolation process.

In one possible implementation, the implementation procedure of step 320 may be: performing coil channel combination on the partial K space data set to obtain a second combined K space data set corresponding to the partial K space data set; performing Fourier transform on the second combined K space data set to obtain an initial image of the heart part; and carrying out interpolation processing on the initial image to obtain a reference image.

As an example, when the initial image is interpolated, the target resolution of the reference image may be determined according to the resolution of each heart image in the heart image sequence, and then the interpolation process may be performed on the initial image according to the target resolution.

In this embodiment, based on the same cardiac imaging protocol parameters, after the cardiac image sequence of the scan object is acquired, a partial K-space dataset of the scan object in a set breath-hold period is acquired through the body coil, so as to shorten the breath-hold time of the scan object, and facilitate implementation. Meanwhile, the uniformity of the reference image acquired by the body coil is good, so that the uniformity of the heart image sequence can be improved by using the reference image to perform uniformity correction on the heart image sequence.

Further, in order to ensure that the cardiac image sequence and the reference image can be better aligned and have the same resolution, in the step 220, the implementation process of performing the first image transformation processing on each K-space dataset may further be: firstly, acquiring candidate K space data sets with the same filling positions as part of the K space data sets from all the K space data sets; coil channel combination is carried out on each candidate K space data set, and a first combined K space data set corresponding to each candidate K space data set is obtained; and carrying out Fourier transform on each first combined K space data set to obtain a heart image sequence.

That is, when a cardiac image sequence is generated from a plurality of K-space data sets acquired by the local coil, not all K-space data is adopted, but partial K-space data having the same filling position as that of a partial K-space data set acquired by the body coil is acquired from the K-space data set acquired by the local coil as a candidate K-space data set, and the candidate K-space data set is further used for generating the cardiac image sequence, so that the imaging rate is improved by reducing the data processing amount under the condition of ensuring that the tissue structure of the cardiac region is clear.

Based on the above description, as an example, see the scanning sequence diagram shown in fig. 4. In the set breath-hold period, the heart image sequence is acquired through the local coil in front of the solid line frame, and the solid line frame is the part which is acquired in the breath-hold period in a supplementary mode in the embodiment of the application, namely, the process of acquiring the reference image through the body coil, wherein the reference image is used for determining the coil sensitivity distribution factor so as to correct the uniformity of the heart image sequence.

Wherein RF in fig. 4 represents a radio frequency pulse, gss represents a slice selection gradient pulse, and Gpe represents a gradient pulse in a phase encoding direction; gro represents gradient pulses in the frequency encoding direction. Further, in fig. 4, the first 180 ° is a non-selective layer inversion pulse, and the second 180 ° is a selective layer inversion pulse (gradient in Gss direction).

In one embodiment, as shown in fig. 5, the step 120 of performing the uniformity correction processing on the cardiac image sequence according to the reference image to obtain a specific implementation process of the corrected cardiac image sequence may include the following steps:

step 510: and determining a coil sensitivity distribution factor corresponding to each heart image in the heart image sequence according to the reference image and the heart image sequence.

Because the tissue structure information obtained after the local coil and the body coil scan the heart part is approximately the same, the tissue structure information can be eliminated after the local coil and the body coil are divided, and therefore the coil sensitivity distribution factors corresponding to each heart image in the heart image sequence can be determined based on the reference image.

In one possible implementation, the implementation procedure of step 510 may be: dividing the reference image by each heart image in the heart image sequence, and determining the coil sensitivity distribution factors corresponding to each heart image according to the division result.

As one example, the coil sensitivity distribution factor affecting the image uniformity can be calculated by the following equation (1).

Wherein Ref _VTC Representing a reference image, L _x Representing each coil unit in the local coil, S _x Representing the sensitivity distribution factors of the individual coil units in the local coil.

It should be noted that, since the local coil has an uneven spatial sensitivity distribution, and the spatial sensitivity distribution of the local coil is drastically reduced with distance from the center of the coil, an image of the entire FOV cannot be simultaneously seen through the local coil. The sensitivity distribution factor of each coil unit can be calculated through the formula (1), and further, based on the sensitivity distribution factor of each coil unit, the uniformity correction is performed on the heart image acquired by each coil unit.

Step 520: and carrying out uniformity correction processing on each heart image according to the coil sensitivity distribution factors corresponding to each heart image to obtain a corrected heart image sequence.

The coil sensitivity distribution factors corresponding to the coil units can be used as correction coefficients of the coil units to perform uniformity correction processing on the heart images.

In one possible implementation, the implementation procedure of step 520 may be: and determining the coil sensitivity distribution factors corresponding to the heart images according to the coil sensitivity distribution factors corresponding to the coil units and the corresponding relation between the coil units and the heart images. Further, each heart image is multiplied by its corresponding coil sensitivity distribution factor to obtain a corrected heart image sequence.

As one example, a corrected cardiac image sequence may be acquired by the following equation (2).

F _x ＝S _x ·f _x (2)

Wherein S is _x Representing the sensitivity distribution factor, f, of each coil unit in a local coil _x Representing cardiac images corresponding to each coil unit in the local coil, F _x Representing the corrected heart image.

In this embodiment, according to the reference image acquired by the body coil and the cardiac image sequence acquired by the local coil, the coil sensitivity distribution factor corresponding to each cardiac image in the cardiac image sequence is calculated, and then, according to the coil sensitivity distribution factor, the uniformity correction is performed on the cardiac image sequence, so that the image uniformity of the cardiac image sequence is improved.

In summary, as shown in fig. 6, the present application also provides another image uniformity correction method, which is also described by taking the application of the method to a computer device as an example, and includes the following steps:

step 610: in a set breath-hold period of a heart part of a scanning object, a plurality of K space data sets of the heart part acquired by a local coil and a part of K space data sets of the heart part acquired by a body coil are respectively acquired.

The acquisition time of the local coil acquisition K space data set is different from the acquisition time of the body coil acquisition part K space data set.

Step 620: candidate K-space datasets are acquired from each K-space dataset that are the same as filling locations in the partial K-space dataset based on the plurality of K-space datasets acquired by the local coil.

Step 630: and carrying out coil channel combination on each candidate K space data set to obtain a first combined K space data set corresponding to each candidate K space data set.

Step 640: and carrying out Fourier transform on each first combined K space data set to obtain a heart image sequence.

That is, the cardiac image sequence is generated from a plurality of K-space data sets acquired by the local coil.

Step 650: and performing second image transformation processing on the partial K space data set acquired by the body coil to obtain a reference image.

That is, the reference image is generated from a partial K-space dataset acquired by the body coil.

Thus, through steps 610-650 described above, a sequence of cardiac images acquired by the local coils and a reference image acquired by the body coil may be obtained.

The acquisition time of the heart image sequence is before the acquisition time of the reference image, and the heart image sequence and the reference image correspond to a set breath-hold period of the heart part of the scanning object. That is, during a set breath-hold period, a sequence of cardiac images is acquired through the local coil and then a reference image is acquired through the body coil.

Because the reference image is acquired immediately after the heart image sequence, and the acquisition time is shorter, the physiological parameter consistency of the scanned object between the heart image sequence acquisition period and the reference image acquisition period is higher, and the possibility of the scanned object moving in the acquisition process is smaller and can be ignored.

Optionally, to shorten the acquisition time of the reference image and reduce the artifact brought by the motion of the scanned object, when the reference image is acquired through the body coil, a partial fourier technique, a partial parallel acquisition (Partiell Parallel Acquisition, PPA) technique, a compressed sensing (Compressed Sensing, CS) technique and the like can be comprehensively applied, so that the data acquisition amount and the acquisition time of the reference image are shortened, and the possibility of introducing motion information in the reference image is reduced.

The partial Fourier technology only collects 1/2 more magnetic resonance signal data of the K space, and the rest data are obtained through symmetry of the K space, so that the imaging technology of filling the whole K space is completed, and the imaging speed of a reference image can be improved. The PPA technique collects only a portion (1/2, 1/3, 1/4, etc.) of the phase-encoded line data and then applies special rendering to that portion of the data to render the missing K-field lines, thereby obtaining a complete FOV image for only a portion of the time. The CS technique collects small amounts of K-space data and restores complete information from these small amounts of data to expedite imaging based on global information of the original signals contained in the data.

Step 660: and determining a coil sensitivity distribution factor corresponding to each heart image in the heart image sequence according to the reference image and the heart image sequence.

Specifically, based on the above formula (1), the coil sensitivity factor corresponding to each cardiac image in the cardiac image sequence is calculated by the image uniformity ratio between the reference image and the cardiac image corresponding to each coil unit in the local coil.

Step 670: and carrying out uniformity correction processing on each heart image according to the coil sensitivity distribution factors corresponding to each heart image to obtain a corrected heart image sequence.

Specifically, based on the above formula (2), for each heart image in the heart image sequence, a corrected heart image is acquired from the product between the heart image corresponding to each coil unit and the sensitivity distribution factor corresponding to the coil unit.

Step 680: and based on the corrected heart image sequence, carrying out fusion processing on the plurality of heart images subjected to uniformity correction processing to obtain a target magnetic resonance image of the heart part.

Optionally, the heart image information corresponding to part of the coil units can be selectively acquired to form spatial weighting by combining the working rule of the heart and/or the image characteristics of the heart image sequence. And then, according to the imaging weight of each heart image, weighting and fusing the plurality of heart images to obtain a target magnetic resonance image of the heart part.

The implementation principle and technical effects of each step in the image uniformity correction method provided in this embodiment are similar to those of each method embodiment, and specific limitation and explanation can be referred to each method embodiment, and are not repeated here.

In summary, as shown in fig. 7, the present application also provides another image uniformity correction method, which is also described by taking the application of the method to a computer device as an example, and includes the following steps:

step 710: in a set breath-hold period of a heart part of a scanning object, a pre-scanning image obtained by pre-scanning the heart part is acquired through a local coil or a body coil.

The pre-scanning image and the reference image are acquired in the same mode, and are realized in a downsampling mode. That is, a partial K-space dataset of the K-space central region is acquired by a local coil or volume coil, generating a pre-scan image of the heart site.

Step 720: acquiring a heart image sequence acquired by a local coil and a reference image acquired by a body coil in a set breath-hold period; the acquisition instant of the sequence of heart images precedes the acquisition instant of the reference image.

Wherein, the realization process of generating the cardiac image sequence by collecting a plurality of K-space data sets of the cardiac part in the breath-hold period through the local coil can be seen in the corresponding embodiment of fig. 2; the implementation process of generating the reference image by undersampling the heart part by the body coil acquisition may refer to the embodiment corresponding to fig. 3. And will not be described in detail herein.

Optionally, in order to shorten the acquisition time of the reference image and reduce the artifact brought by the motion of the scanned object, a part of fourier technology, PPA technology, CS technology and the like can be comprehensively applied, so that the data acquisition amount and the acquisition time of the reference image are shortened.

It should be noted that, the set breath-hold periods of the step 710 and the step 720 may be the same breath-hold period, and the set breath-hold periods of the heart image sequence and the reference image obtained in the step 720 may be the same breath-hold period.

Step 730: and determining a coil sensitivity distribution factor corresponding to each heart image in the heart image sequence according to the reference image and the heart image sequence.

Step 740: and carrying out uniformity correction processing on each heart image according to the coil sensitivity distribution factors corresponding to each heart image to obtain a corrected heart image sequence.

Step 750: and based on the corrected heart image sequence, carrying out fusion processing on the plurality of heart images subjected to uniformity correction processing to obtain a target magnetic resonance image of the heart part.

Step 760: a target magnetic resonance image of the heart region is corrected for homogeneity based on the pre-scan image.

That is, the uniformity of the heart images acquired by the coil units is corrected by referring to the images, so that the imaging quality of each heart image is improved; further, after the target magnetic resonance image is generated through the plurality of cardiac images, the uniformity of the target magnetic resonance image is corrected through the pre-scanning image, so that the uniformity of the target magnetic resonance image is further improved, and the final imaging quality is better.

It should be understood that, although the steps in the flowcharts related to the embodiments described above are sequentially shown as indicated by arrows, these steps are not necessarily sequentially performed in the order indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least some of the steps in the flowcharts described in the above embodiments may include a plurality of steps or a plurality of stages, which are not necessarily performed at the same time, but may be performed at different times, and the order of the steps or stages is not necessarily performed sequentially, but may be performed alternately or alternately with at least some of the other steps or stages.

Based on the same inventive concept, the embodiment of the application also provides an image uniformity correction device for realizing the image uniformity correction method. The implementation of the solution provided by the apparatus is similar to that described in the above method, so the specific limitation of one or more embodiments of the image uniformity correction apparatus provided below may be referred to the limitation of the image uniformity correction method hereinabove, and will not be repeated herein.

In one embodiment, as shown in fig. 8, an image uniformity correction apparatus 800 is provided, the apparatus 800 comprising: an acquisition module 810, a correction module 820, and an imaging module 830, wherein:

an acquisition module 810 for acquiring a sequence of cardiac images acquired by the local coil and a reference image acquired by the body coil, respectively; the acquisition time of the heart image sequence is different from the acquisition time of the reference image, and the heart image sequence and the reference image correspond to a set breath-hold period of a heart part of a scanning object;

the correction module 820 is configured to perform uniformity correction processing on the cardiac image sequence according to the reference image, so as to obtain a corrected cardiac image sequence;

an imaging module 830 for generating a target magnetic resonance image of the heart site from the corrected sequence of heart images.

In one embodiment, the acquiring module 810 includes:

a first data acquisition unit for acquiring a plurality of K-space data sets of a heart part within a set breath-hold period through a local coil;

and the first image processing unit is used for carrying out first image transformation processing on each K space data set to obtain a heart image sequence.

In one embodiment, the acquiring module 810 includes:

The second data acquisition unit is used for undersampling the heart part through the body coil in a set breath-hold period so as to obtain a partial K space data set;

and the second image processing unit is used for carrying out second image transformation processing on the partial K space data set to obtain a reference image.

In one embodiment, a first image processing unit includes:

a data acquisition subunit, configured to acquire, from each K-space dataset, a candidate K-space dataset that has the same filling position as that of the partial K-space dataset;

the first channel merging subunit is used for carrying out coil channel merging on each candidate K space data set to obtain a first merged K space data set corresponding to each candidate K space data set;

and the first transformation subunit is used for carrying out Fourier transformation on each first combined K space data set to obtain a heart image sequence.

In one embodiment, the second image processing unit includes:

a second channel merging subunit, configured to perform coil channel merging on the partial K-space dataset to obtain a second merged K-space dataset corresponding to the partial K-space dataset;

the second transformation subunit is used for carrying out Fourier transformation on the second combined K space data set to obtain an initial image of the heart part;

And the image interpolation subunit is used for carrying out interpolation processing on the initial image to obtain a reference image.

In one embodiment, the correction module 820 includes:

the determining unit is used for determining coil sensitivity distribution factors corresponding to each heart image in the heart image sequence according to the reference image and the heart image sequence;

and the correction unit is used for carrying out uniformity correction processing on each heart image according to the coil sensitivity distribution factors corresponding to each heart image to obtain a corrected heart image sequence.

In one embodiment, the imaging module 830 is specifically configured to:

The respective modules in the above-described image uniformity correction apparatus may be implemented in whole or in part by software, hardware, or a combination thereof. The above modules may be embedded in hardware or may be independent of a processor in the computer device, or may be stored in software in a memory in the computer device, so that the processor may call and execute operations corresponding to the above modules.

In one embodiment, a computer device is provided, which may be a terminal, and the internal structure thereof may be as shown in fig. 9. The computer device includes a processor, a memory, a communication interface, a display screen, and an input device connected by a system bus. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The communication interface of the computer device is used for carrying out wired or wireless communication with an external terminal, and the wireless mode can be realized through WIFI, an operator network, NFC (near field communication) or other technologies. The computer program is executed by a processor to implement an image uniformity correction method. The display unit of the computer equipment can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer equipment can be a touch layer covered on the display screen, can also be a key, a track ball or a touch pad arranged on the shell of the computer equipment, and can also be an external keyboard, a touch pad or a mouse and the like.

It will be appreciated by persons skilled in the art that the architecture shown in fig. 9 is merely a block diagram of some of the architecture relevant to the present inventive arrangements and is not limiting as to the computer device to which the present inventive arrangements are applicable, and that a particular computer device may include more or fewer components than shown, or may combine some of the components, or have a different arrangement of components.

In one embodiment, a computer device is provided comprising a memory and a processor, the memory having stored therein a computer program, the processor when executing the computer program performing the steps of:

The computer device provided in the foregoing embodiments has similar implementation principles and technical effects to those of the foregoing method embodiments, and will not be described herein in detail.

In one embodiment, a computer readable storage medium is provided having a computer program stored thereon, which when executed by a processor, performs the steps of:

The foregoing embodiment provides a computer readable storage medium, which has similar principles and technical effects to those of the foregoing method embodiment, and will not be described herein.

In one embodiment, a computer program product is provided comprising a computer program which, when executed by a processor, performs the steps of:

The foregoing embodiment provides a computer program product, which has similar principles and technical effects to those of the foregoing method embodiment, and will not be described herein.

Those skilled in the art will appreciate that implementing all or part of the above described methods may be accomplished by way of a computer program stored on a non-transitory computer readable storage medium, which when executed, may comprise the steps of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in embodiments provided herein may include at least one of non-volatile and volatile memory. The nonvolatile Memory may include Read-Only Memory (ROM), magnetic tape, floppy disk, flash Memory, optical Memory, or the like. Volatile memory can include random access memory (Random Access Memory, RAM) or external cache memory. By way of illustration, and not limitation, RAM can be in the form of a variety of forms, such as static random access memory (Static Random Access Memory, SRAM) or dynamic random access memory (Dynamic Random Access Memory, DRAM), and the like.

The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.

Claims

1. An image uniformity correction method, the method comprising:

2. The method of claim 1, wherein the acquiring a sequence of cardiac images acquired by a local coil comprises:

acquiring a plurality of K-space data sets of the heart site within the set breath-hold period by the local coil;

and performing first image transformation processing on each K space data set to obtain the heart image sequence.

3. The method of claim 2, wherein the acquiring the reference image acquired by the body coil comprises:

undersampling the cardiac region by the body coil during the set breath-hold period to obtain a partial K-space dataset;

and performing second image transformation processing on the partial K space data set to obtain the reference image.

4. A method according to claim 3, wherein said performing a first image transformation on each of said K-space data sets to obtain said sequence of cardiac images comprises:

Acquiring candidate K space data sets with the same filling positions as the partial K space data sets from the K space data sets;

performing coil channel combination on each candidate K space data set to obtain a first combined K space data set corresponding to each candidate K space data set;

and carrying out Fourier transform on each first combined K space data set to obtain the heart image sequence.

5. A method according to claim 3, wherein said performing a second image transformation on said partial K-space dataset to obtain said reference image comprises:

and carrying out interpolation processing on the initial image to obtain the reference image.

6. The method according to any one of claims 1-5, wherein said performing a uniformity correction process on said sequence of cardiac images from said reference image comprises:

And carrying out uniformity correction processing on each heart image according to the coil sensitivity distribution factors corresponding to each heart image to obtain the corrected heart image sequence.

7. The method of claim 6, wherein generating a target magnetic resonance image of the cardiac site from the corrected sequence of cardiac images comprises:

8. An image uniformity correction apparatus, the apparatus comprising:

9. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor implements the steps of the method of any of claims 1 to 7 when the computer program is executed.

10. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the method of any of claims 1 to 7.